nmoffatt

iTrader: (15)

Starting a new thread as my questions is a bit different from the previous thread I bumped. I've been studying the wiring diagram and countless posts over the last couple of days and am completely stuck.

Problem: Relay #1 that controls the cooling fans when the AC is turned on no longer de-energizes when the ignition is turned off (Accessories ON or key removed). So in my case the cooling fans never turn off and will keep running until the battery is dead. When the ignition is turned on the relay de-energizes (fans turn off) and the AC works normally. The relay will re-energize once I click the AC button and turn the fan on any speed and de-energize once I turn the AC off.

How I got here: I've been running the PFC for a few weeks now and decided to do the PFC relay fix to get the AC going again. That part worked and the AC is fine but I noticed right away that the fans would come on the moment I reconnected the negative terminal on the battery. Nothing else was touched which is weird. Car is also stock except for a downpipe.

What I have tried so far:

1) Came across the Mazda fan recall in my searching. Thought maybe this might have something to do with it so I removed both harnesses. Unfortunately this had no effect.
2) Tested all 4 relays and they all work fine. This is where I found that it was relay #1 that was causing the issue.
3) Rolled back the PFC AC fix and reconnected 1E back the way it was and retested. No help there either.
4) Unplugged the PFC altogether and re-tested. Same behavior. Fan control for the AC should not be affected whether the ECU is plugged in from what I am reading. Like I mentioned it works as expected when the key is turned to ignition.
5) Put back the stock ECU and retested. Same result.
6) Checked the thermoswitch on the AC unit and tested as per the FSM and it passed.
7) Set up a multi meter on the ground going into the relay coil. This is supposed to be a switched ground once the AC button is pushed to energize the relay and turn the fans on. (positive side always has power from the battery so the ground controls the fans). I can see it is always grounded UNLESS I turn the key to ignition. Then the ground switched off.

So what I am banging my head against the wall to figure out is what controls this ground signal to the relay? At first I thought it had something to do with what I changed with the AC fix but have recently come to accept that there was another issue that came to the surface that I stumbled across or disturbed. Any advice would be appreciated.

Thanks!

nmoffatt

iTrader: (15)

Figured out the issue and just wanted to document it here in case it can help someone later on. I tapped the battery lead instead of the ignition lead thinking it would not make a difference for the new relay. The 12V current from the battery (85) flows to the ground wire on the cooling fan relay coil (violet wire) by design on the relay (86). The positive wire on the cooling relay coil (black/yellow) is grounded when the ignition is off so the relay is triggered once the battery is connected. I did not expect this behavior...

Once the ignition is turned the black/yellow wire is powered 12V (along with all the other 3 relays) and the violet wire is NOT grounded with 0V. From that point on the AC/Fan switch switch grounds the violet wire which turns on the cooling fan. This also sends a much healthier ground signal through the relay to the PFC and fixes the AC issue.

if I followed the instructions to the letter it would have avoided this whole hassle but at least I have have learned in depth the wiring of the cooling fan system and tested everything !